A Multicomponent Body‐Centered Cubic Superconducting Alloy with Exceptional Mechanical Robustness at 4.2 Kelvin

ABSTRACT The ductile‐to‐brittle transition poses a persistent challenge for body‐centered cubic (BCC) structure superconducting alloys at liquid helium temperature (4.2 K), where intrinsic brittleness frequently leads to premature material failure and severely restricts their application in extreme environments. Here we present a BCC multicomponent V‐Nb‐Ti‐Mo superconducting alloy that achieves a high fracture elongation of ∼16% while maintaining pronounced strain‐hardening capacity of ∼620 MPa at 4.2 K. This exceptional ultra‐cryogenic ductility surpasses that of nearly all reported superconducting materials, and even BCC structured alloys. The rarely reported nanoscale orthorhombic martensitic transformation and the local chemical fluctuations with V‐enriched nanoclusters considerably promote the strain‐hardening capacity. Unlike traditional BCC alloys dominated by screw dislocations, a high density of non‐screw dislocations also formed to facilitate elongation. Plenty of kink bands, which are generally difficult to form at 4.2 K, delay the fracture process. This study not only offers a viable solution to the long‐standing cryogenic brittleness problem of BCC structure alloys, but also introduces a superconducting material with superior mechanical reliability for extreme‐condition applications.